69 fb 340 barracuda freeze plugs/replace ??

On my 67 273, I had 1 plug dripping behind the starter. The 1 forward of that was damp/seeping. I replaced same 2 on pass' side also, 4 total. Went under with a garden hose and various tools and cleaned chunks of crap out of the block. The previous owner had poured in Barsleak annually.
The plugs I used have a closed nut in the center that is tightened to expand the plug. Dorman product? I forget.
Took previous owners 7 lb cap off and installed a new 18 lb cap. Added coolant recovery bottle too. No problem since. About 10 years. I did pull that bottle to flush a little nasty from the bottom of it 3 times over 3 years.